This invention relates generally to the field of the manufacture of endless looped transfer or conveyor belts having a repetitive pattern of transfer apertures. More particularly, this invention relates to a process for manufacturing such a belt, including the steps of creating the apertures, cutting the belt to form a splice joint, and joining the belt to create an endless looped belt, whereby loss of registration is kept to a minimum.
Endless transfer belts are well-known. The belts are used to pick up components in a manufacturing process and move them to another location for further manufacturing steps. A common example is in the making of cans. The lids are stamped out, picked up by the apertures in the transfer belt and moved to successive locations where forming operations are carried out and the lids are eventually attached to the cans. Typical transfer belts can be twenty, thirty or more feet in length, and move at speeds faster than the eye can register. A major problem in these operations is the down time which results when a transfer belt gets out of register or loses some of the objects it is carrying.
While OEM belts can be manufactured to very good tolerances, replacement belts suffer from a lack of registration. To create replacement belts, it is current practice to create the repetitive aperture pattern by eyeball alignment--that is, a set of apertures is punched, then the belt is advanced to a mark and the next set of apertures is punched. Splice joints are cut and the two free ends are spliced using metal splices or glues. The registration is usually difficult to maintain using these methods, and loss of registration of up to 3/4 inches per 20 feet are common. Additionally, the metal splices can loosen and damage the expensive machinery and the glue joints eventually break. With tens of thousands of transfers occurring per hour, time lost to necessary replacement or re-registration of belts is costly.
A novel and unique process for creating apertured endless looped transfer belts with minimal loss of registration has been invented. The process comprises the steps of creating the apertures in the belt material, creating the splice joint and joining the belt ends to each other using melt flow under pressure. The resulting belts have extremely low loss of registration--less that 1/4 inches typically for a twenty foot belt. The splice joint is strong and flexible, such that it will not separate over time. The apertures likewise are extremely accurate in dimensions and relative location, even at the splice joint.